MARIANA DELEANU, GABRIELA M. SANDA, CAMELIA S. STANCU, MONA E. POPA, ANCA V. SIMA PROFILES OF FATTY ACIDS AND THE MAIN LIPID PEROXIDATION PRODUCTS OF HUMAN ATHEROGENIC LOW DENSITY LIPOPROTEINS
Cardiovascular diseases (CVD), a worldwide leading cause of mortality and morbidity, are generated mainly by atherosclerosis. The serum fatty acids (FA) and some of their peroxidation products, such as 4-hydroxy-trans-2-nonenal (4-HNE) and malondyaldehyde (MDA), are known risk factors for CVD. Our aim was to determine in atherogenically-modified low-density lipoproteins (LDL), either oxidized or glycated, the FA composition, quantify the levels of 4-HNE, MDA and of cholesterol’s main oxidation product, 7-kethocholesterol (7-KC). Profiles of FA, conjugated dienes , 4-HNE, MDA and 7-KC were determined in native LDL (nLDL) isolated from blood donors from the Hematology Center, Bucharest, copper-oxidized LDL (oxLDL) and non-enzymatically glycated LDL (gLDL). The FA composition was determined by Gas Chromatography with a flame ionization detector and the conjugated dienes by absorbtion in UV at 234 nm. Free 4-HNE and 7-KC levels were determined by Gas-Chromatography-Triple Quadrupol Mass Spectrometry in Electron Ionization mode and total MDA by reversed-phase Ultra High Performance Lichid Chromatography. Results showed that the polyunsaturated fatty acids (PUFAs) were totally reduced in oxLDL (except linoleic acid) and decreased in gLDL, while the monounsaturated fatty acids remained almost unchanged in both oxLDL and gLDL. Lipid peroxidation products increased as follows: conjugated dienes were significantly increased both in gLDL (29%, p<0.05) and oxLDL (1.5 fold higher, p<0.01) compared to nLDL; free 4-HNE level in oxLDL (2.75±1.01 nmoles/mg protein) was ~100 times the level in nLDL (0.02±0.01 nmoles/mg protein), while gLDL (0.05±0.02 nmoles/mg protein) had only twice the nLDL level; MDA levels in oxLDL were statistically increased (1.05±0.44 nmoles/mg protein) compared to nLDL (0.05± 0.02 nmoles/mg protein) and to gLDL (0.19±0.05 nmoles/mg protein); 7-KC level was significantly increased in oxLDL (674.39± 207.70 nmoles/mg protein) and gLDL (1.21± 0.32 nmoles/mg protein) compared to nLDL (0.13± 0.04 nmoles/mg protein). Our data demonstrate that the alteration of the FA composition of modified LDL has two negative consequences: (i) the reduction of PUFA levels, most importantly the essential w-3 and w-6 fatty acids, and (ii) the increase of the main peroxidation products of FA and cholesterol such as conjugated dienes, free 4-HNE, MDA and 7-KC, transforming LDL into atherogenic lipoproteins.